1. Field
Communication systems may benefit from signaling for resource mapping. For example, third generation partnership project (3GPP) long term evolution advanced (LTE-Advanced) may benefit from signaling for enhanced downlink control channel (ePDCCH) resource mapping in support of coordinated multipoint (CoMP) transmission.
2. Description of the Related Art
Among considerations with respect to an enhanced downlink (DL) control channel are consideration regarding the enhanced physical downlink control channel (ePDCCH) coding chain rate-matching is used around the common reference signal (CRS), PDCCH region and PBCH/PSS/SSS as follows. For example, it may be that a resource element (RE) that collides with any other signal is not used for ePDCCH. Moreover, coding chain rate-matching may be used around a CRS, a new antenna port on new carrier type (NCT), a region up to the physical downlink shared channel (PDSCH) starting position, and/or a physical broadcast channel (PBCH) and primary synchronization signal/secondary synchronization signal (PSS/SSS) if ePDCCH transmission in these physical resource block (PRB) pairs is supported.
The positions of these signals listed above may be known to the UE when the ePDCCH is transmitted from a single transmission point (TP). However, in some scenarios, similar to the data channel PDSCH, the ePDCCH may also benefit from cooperative multiple point transmission (CoMP). The CoMP support for the PDSCH typically operates in a transparent manner to the UE.
Control signaling support for the CoMP operation and ongoing ePDCCH design may need to be compatible. Moreover, to have a future proof ePDCCH design, the design may need to take into account the potential CoMP support for the ePDCCH. When the ePDCCH employs any CoMP scheme, such as joint transmission (JT) or dynamic point selection (DPS) in scenarios where the cooperating transmission points (TP) have a different cell ID, the user equipment (UE) may need to know the position of the CRS and PDCCH region for each ePDCCH blind decoding candidate.
This is not a problem for scenarios where the cooperating TPs have the same shared cell ID. In such a case, CRS positions and the PDCCH region for all transmission points are same. In a CoMP scenario, with a Macro-Pico type heterogeneous network (HetNet), assuming that the DPS is used for the ePDCCH, in one subframe the ePDCCH may be transmitted from the Marco cell, then REs used for e.g. the CRSs of the Macro cell may need to be mapped around. In another subframe, the ePDCCH may be transmitted from the Pico cell, and accordingly the REs used for e.g. CRSs of the Pico cell may need to be mapped around for the ePDCCH. If the JT from both the Macro and Pico is applied, then the REs used for e.g. CRSs of both cells may need to be mapped around.
One approach solving the problem for the PDSCH case is to provide to the UE the positions of other signals such as CRS for the PDSCH resource mapping with CoMP operation. The downlink control information (DCI) carried by the PDCCH or ePDCCH would be used to provide the CRS positions to the UE. However, such an approach is not possible for the ePDCCH with CoMP operation, since the DCI is only accessible to the UE after it correctly decodes the ePDCCH. However, due to the coding chain rate matching approach, the CRS position information to decode the ePDCCH.
Currently the resource mapping around CRS is necessary for ePDCCH does not yet take into account the potential CoMP support. Thus, there are no existing approaches for coping with the CRS and PDCCH region signaling to support the CoMP operation for ePDCCH.